Download Fault Analysis

Fault Analysis
• Analysis of power system parameters
resulting from a ground or line to line fault
somewhere in the system
• Simulator contains a tool for analyzing
faults in an automatic fashion
• Can perform single and three phase faults
©2008 PowerWorld Corporation
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Fault Analysis
• Fault types include:
–
–
–
–
Single line to ground
Line to line
Double line to ground
Three phase balanced
• The general fault analysis tool can be
accessed in run mode by: Tools ribbon tab
ÆFault Analysis
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Setting the Fault Location
• Information about the fault location can be filled in
manually
• Alternatively, you can right-click on a bus or transmission
line on the oneline diagram, and select Fault… from the
menu to have the fault location fields automatically set
– Selecting Fault… for a bus will set the bus number field
– Selecting Fault… for a transmission line will set the from and to
bus numbers, the circuit identifier, and the approximate line
location as a percentage of the length of the line
– Any of these fields can still be changed manually
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Select Type of Fault
• Determines which calculations to perform
– Line to ground: assumes phase A to ground
– Line to line: assumes phase B to phase C
– Line to line to ground: assumes phase B to phase C to
ground
– Three phase balanced
• A non-zero impedance to ground can be defined on
the options tab, default is 0 (except for line to line)
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Fault Dialog: Data
Set type of
fault
Current through
the fault
Devices
listed here
depend on
bus or inline fault
Results of analysis are displayed
in the grids on these five pages
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Sequence Data for Fault Analysis
• By default, sequence data for fault analysis is not
stored with load flow data
• Sequence data can be loaded from the Options
page
– PowerWorld Auxiliary file (*.aux)
– PTI Sequence Data file (*.seq)
• Sequence data can similarly be saved to the same
types of external files; however, Simulator will
store sequence data with the load flow case
(*.pwb) if you save the case after loading the
sequence data
©2008 PowerWorld Corporation
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Sequence Data for Fault Analysis
• Sequence data is required for various
devices:
– Generators
• Internal sequence impedances
• Neutral to ground impedance
– Transmission Lines
• Zero sequence impedance
• Zero sequence line shunt admittance
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Sequence Data for Fault Analysis
– Transformers
• Zero sequence impedance and line shunt admittance
• Phase shifts, entered as Phase in the load flow data
• Transformer grounding configuration, as a
combination of Wye, Grounded Wye, and Delta
connections
– Loads
• Negative and zero sequence load, as an admittance
• Set on a bus-basis, with admittance given is total
admittance for all loads at that bus
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Sequence Data for Fault Analysis
• Transmission line mutual impedance
– Zero sequence mutual impedance between part
or all of two transmission lines
– Displayed on Options tab
• Fault data for all devices (except mutual
impedances) can be entered on the
Information Dialogs
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Fault Analysis: Options
Impedance to
ground at the fault
Load and save sequence data
as a text file
Mutual
impedance
records
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Fault Analysis Example
• Open B7FaultExample.pwb
– No sequence data exists, so all fault analysis data fields
are set to defaults
• Run the Fault Analysis tool from run mode by:
Tools ribbon tab ÆFault Analysis
• From the Fault Options tab, select Load Data
– Confirm replacing sequence data
– Load B7FaultExample.aux
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Fault Analysis Example
• Switch to the Fault Data tab, and select fault
bus number 3
• Leave as bus fault, single line to ground
• Click Calculate
– The case will be solved first to make sure the
analysis will be valid
– The fault analysis calculation is a linearized
calculation about the operating point
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Fault Analysis Example
• Results are displayed on the five tab sheets on the
Fault Data page
– Per phase bus voltage magnitude (p.u.) and angle (deg.)
– Per phase branch from and to bus current magnitude,
with current direction at BOTH ends defined AWAY
from the terminal bus
– Per phase generator current magnitude and angle (deg.),
with current direction defined OUT of the generator
– Per phase load and switched shunt magnitude, with
current direction defined AWAY from the terminal bus
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Fault Analysis Visualization of
Results
• Voltages and currents calculated during
Fault Analysis can be visualized on a
oneline diagram
– In the Data Type Shown on Oneline box, select
a single phase or all phases
– When Data Type Shown is changed to phase or
phases, Simulator searches for and replaces the
following types of text fields on the oneline
diagram:
©2008 PowerWorld Corporation
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Fault Analysis Visualization of
Results
• Bus voltage fields replaced with phase voltage magnitude(s) in
p.u.
• Bus angle fields replaced with phase voltage angle(s) in
degrees
• Branch MW or Amp fields replaced with phase current
magnitude(s) in Amps or p.u., as specified
• Branch MVAR fields replaced with phase current angle(s) in
degrees
• Generator MW fields replaced with phase current magnitude(s)
in Amps or p.u., as specified
• Generator MVAR fields replaced with phase current angle(s)
in degrees
©2008 PowerWorld Corporation
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Fault Analysis Visualization of
Results
Only fields
switched to
fault analysis
results will
remain on
oneline
Currents shown
are magnitude
only; would
need to include
angles to
determine
direction
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Fault Analysis Visualization of
Results
• The phase of the fault data displayed on the
diagram can be quickly toggled to a
different phase by clicking on the dropdown arrow on the Fault Analysis toolbar
button and choosing a new visualization
setting
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In-Line Faults
• Calculated based on a location given as a
percentage distance from the From end of
the line
• Inserts a temporary bus and line segments
representing the fault point of the line;
reflected on the oneline diagram
• Calculations performed the same as a bus
fault at the temporary bus
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Fault Analysis: Final Notes
• The fault analysis form can be closed while a fault
is calculated without clearing the fault; the values
will remain in memory until manually cleared or
the case is saved or closed
• A Double Line fault automatically uses a Fault
Impedance of 999+j999 and ignores the Fault
Impedance settings; use a Double Line to Ground
fault to specify a desired Fault Impedance
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Fault Analysis: Final Notes
• Before visualizing fault analysis currents in
p.u., you may need to first change the
number of decimal places for the branch
and generator MW and MVAR fields
• Once Sequence Data is loaded from an
external file, saving the case file will store
the sequence data with the *.pwb as well
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